1. Field of the Invention
The present invention relates to a dual-band mobile communication device and a related antenna structure; more particularly, the present invention relates to a dual-band mobile communication device and a related antenna structure having a dual-band inductively-coupled element capable of exciting two resonant modes as well as enhancing bandwidths in both a lower operating band and a higher operating band of the antenna at the same time.
2. Description of the Related Art
With the vigorous development of mobile communication techniques, a variety of wireless communication products keep coming out one after another, and therefore the mobile communication devices have been tightly bonded to people's daily lives, wherein mobile phones are most popular and most widely used among all these communication products. Currently, it is the trend to design a mobile phone in a compact and small size. However, whether the operating bandwidth of a conventional mobile phone antenna is in a low operating band (such as GSM850/900) or a high operating band (such as GSM1800/1900/UMTS), it may greatly influence the size changes of the system ground plane. Therefore, if there is a need to directly applying a conventional mobile phone antenna in a mobile phone with a small-sized system ground plane, the antenna has to be re-designed due to the reduction of the operating bandwidth. Generally, the size of the antenna has to be enlarged in order to acquire enough operating bandwidth; however, this would significantly increase the difficulty of installing the antenna in a small-sized mobile phone.
For example, a dual-band antenna design for application in a mobile phone is disclosed in Taiwan Patent No. 1308,409 (An internal thin dual-band handset antenna). However, if the length of the system ground plane of such an antenna is shortened, the bandwidths of the low operating band and the high operating band will be affected and thereby reduced. Therefore, the overall size of the antenna needs to be enlarged so as to improve the operating bandwidths.
Therefore, there is a need to provide a dual-band mobile communication device to mitigate and/or obviate the aforementioned problems.